AP PHOTOS: Scenes from the past 48 hours in Boston

A crowd gathers at Boston Common after the final suspect in the Boston Marathon bombing was arrested, Friday, April 19, 2013, in Boston. Marathon bombing suspect Dzhokhar Tsarnaev was captured in Watertown, Mass. The 19-year-old college student wanted in the bombings was taken into custody Friday evening after a manhunt that left the city virtually paralyzed and his older brother and accomplice dead. (AP Photo/Julio Cortez)

People cheer passing police after the arrest of a suspect of the Boston Marathon bombings in Watertown, Mass., Friday, April 19, 2013. Two suspects in the Boston Marathon bombing killed an MIT police officer, injured a transit officer in a firefight and threw explosive devices at police during their getaway attempt. (AP Photo/Matt Rourke)

This still frame from video shows Boston Marathon bombing suspect Dzhokhar Tsarnaev visible through an ambulance after he was captured in Watertown, Mass., Friday, April 19, 2013. The 19-year-old college student wanted in the Boston Marathon bombings was taken into custody Friday evening after a manhunt that left the city virtually paralyzed and his older brother and accomplice dead. (AP Photo/Robert Ray)

FILE - In this Wednesday, April 17, 2013 file photo, a mourner reacts during a candlelight vigil at City Hall in Cambridge, Mass. in the aftermath of Monday's Boston Marathon explosions. Event after nail-biting event, America was rocked this week, in rare and frightening ways, with what felt like an unremitting series of tragedies. (AP Photo/Matt Rourke, File)

FILE - In this Monday, April 15, 2013 file photo, people react as an explosion goes off near the finish line of the 2013 Boston Marathon in Boston. Event after nail-biting event, America was rocked this week, in rare and frightening ways, with what felt like an unremitting series of tragedies. (AP Photo/The Boston Globe, David L Ryan, File) MANDATORY CREDIT: THE BOSTON GLOBE, DAVID L RYAN

FILE - In this Thursday, April 18, 2013 file photo, emergency personnel search the rubble of an apartment destroyed by an explosion at a fertilizer plant in West, Texas. Event after nail-biting event, America was rocked this week, in rare and frightening ways, with what felt like an unremitting series of tragedies. (AP Photo/LM Otero, File)

FILE - In this Wednesday, April 17, 2013 file photo, President Barack Obama hugs Nicole Hockley, mother of Dylan, who was killed in the Newtown School shootings, during a news conference in the Rose Garden of the White House in Washington. The Senate voted down legislation that would have banned assault weapons and expanded background checks of gun buyers. Accompanying the president are former Rep. Gabby Giffords, second from left, Vice President Joe Biden, and other Newtown family members from left, Neil Heslin, father of Jesse Lewis; Jimmy Greene, father of Ana; Mark and Jackie Barden, with their children Natalie and James, who lost Daniel; and Jeremy Richman, father of Avielle, behind the Bardens. (AP Photo/Carolyn Kaster, File)

FILE - In this Friday, April 19, 2013 file photo, federal agents wearing hazardous material suits inspect a trash can outside the house of Paul Kevin Curtis in Corinth, Miss. Curtis is in custody under the suspicion of sending letters covered in ricin to U.S. President Barack Obama and U.S. Sen. Roger Wicker, R-Miss. Event after nail-biting event, America was rocked this week, in rare and frightening ways, with what felt like an unremitting series of tragedies. (AP Photo/Rogelio V. Solis, File)

FILE - In this Thursday, April 18, 2013 file photo, mourners attend a service at St. Mary's Church of the Assumption, a day after an explosion at a fertilizer plant in West, Texas. America was rocked this week, in rare and frightening ways, with what felt like an unremitting series of tragedies. (AP Photo/Charlie Riedel, File)

FILE - In this Tuesday, April 16, 2013 file photo, neighbors sit outside the house of Krystle Campbell's parents in Medford, Mass. Campbell was killed in Monday's explosions at the finish line of the Boston Marathon. America was rocked this week, in rare and frightening ways, with what felt like an unremitting series of tragedies. (AP Photo/Michael Dwyer, File)

President Barack Obama finishes speaking in the Brady Press Briefing Room of the White House in Washington, Tuesday, April 16, 2013, about the Boston Marathon explosions.(AP Photo/Susan Walsh)

A police officer holds a shotgun as an ambulance heads down Franklin Road to the scene of the arrest of a suspect of the Boston Marathon bombings in Watertown, Mass., Friday, April 19, 2013. Two suspects in the Boston Marathon bombing killed an MIT police officer, injured a transit officer in a firefight and threw explosive devices at police during their getaway attempt. (AP Photo/Charles Krupa)

ALTERNATE CROP - This still frame from video shows Boston Marathon bombing suspect Dzhokhar Tsarnaev visible through an ambulance after he was captured in Watertown, Mass., Friday, April 19, 2013. The 19-year-old college student wanted in the Boston Marathon bombings was taken into custody Friday evening after a manhunt that left the city virtually paralyzed and his older brother and accomplice dead. (AP Photo/Robert Ray)

A light beam from a helicopter, top right, aims in the direction of Watertown, Mass., where officials searched for a suspect in the Boston Marathon explosions, Friday, April 19, 2013, in Boston. Officials claim the suspect has hunkered down inside a boat in the yard of a home on Franklin Street. Two suspects in the Boston Marathon bombing killed an MIT police officer, injured a transit officer in a firefight and threw explosive devices at police during their getaway attempt in a long night of violence that left one of them dead. (AP Photo/Julio Cortez)

A crowd reacts to news of the arrest of one of the Boston Marathon bombing suspects during a celebration at Boston Common, Friday, April 19, 2013, in Boston. Boston Marathon bombing suspect Dzhokhar Tsarnaev was captured in Watertown, Mass. The 19-year-old college student wanted in the bombings was taken into custody Friday evening after a manhunt that left the city virtually paralyzed and his older brother and accomplice dead. (AP Photo/Julio Cortez)

Taylor Richard, center, of Belmont, Mass., and Alyssa Kohler, 17, of Cambridge, Mass., wrap themselves in the American Flag in Watertown, Mass., Friday, April 19, 2013. A 19-year-old Massachusetts college student wanted in the Boston Marathon bombing was captured hiding out in a boat parked in a backyard Friday and his older brother lay dead in a furious 24-hour drama that transfixed the nation and paralyzed the Boston area with fear. (AP Photo/Craig Ruttle)

A police officer stands guard at the scene as the search for suspect in the Boston Marathon bombings continues , Friday, April 19, 2013, in Watertown, Mass. Gunfire erupted Friday night amid the manhunt for the surviving suspect in the Boston Marathon bombing, and police in armored vehicles and tactical gear rushed into the Watertown neighborhood in a possible break in the case. (AP Photo/Matt Rourke)

Officials wearing tactical gear stand near an armored vehicle as they search an apartment building for one of two suspects in the Boston Marathon bombing, in Watertown, Mass., Friday, April 19, 2013. Two suspects in the Boston Marathon bombing killed an MIT police officer, injured a transit officer in a firefight and threw explosive devices at police during a getaway attempt in a long night of violence that left one of them dead and another still at large Friday, authorities said as the manhunt intensified for a young man described as a dangerous terrorist. (AP Photo/Julio Cortez)

A police officer enters an apartment building with his dog while searching for a suspect in the Boston Marathon bombings in Watertown, Mass., Friday, April 19, 2013. The bombs that blew up seconds apart near the finish line of the Boston Marathon left the streets spattered with blood and glass, and gaping questions of who chose to attack and why. (AP Photo/Charles Krupa)

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A resident views police in tactical gear conduct a search for a suspect in the Boston Marathon bombings, Friday, April 19, 2013, in Watertown, Mass. Two suspects in the Boston Marathon bombing killed an MIT police officer, injured a transit officer in a firefight and threw explosive devices at police during a getaway attempt in a long night of violence that left one of them dead and another still at large Friday, authorities said as the manhunt intensified for a young man described as a dangerous terrorist.(AP Photo/Matt Rourke)

Police officers walk near a crime scene Friday, April 19, 2013, in Watertown, Mass. A tense night of police activity that left a university officer dead on campus just days after the Boston Marathon bombings and amid a hunt for two suspects caused officers to converge on a neighborhood outside Boston, where residents heard gunfire and explosions.(AP Photo/Matt Rourke)

Police officers aim their weapons Friday, April 19, 2013, in Watertown, Mass. A tense night of police activity that left a university officer dead on campus just days after the Boston Marathon bombings and amid a hunt for two suspects caused officers to converge on a neighborhood outside Boston, where residents heard gunfire and explosions.(AP Photo/Matt Rourke)

This combination of undated photos shows Tamerlan Tsarnaev, 26, left, and Dzhokhar Tsarnaev, 19. The FBI says the two brothers and suspects in the Boston Marathon bombing killed an MIT police officer, injured a transit officer in a firefight and threw explosive devices at police during a getaway attempt in a long night of violence that left Tamerlan dead and Dzhokhar still at large on Friday, April 19, 2013. The ethnic Chechen brothers lived in Dagestan, which borders the Chechnya region in southern Russia. They lived near Boston and had been in the U.S. for about a decade, one of their uncles reported said. (AP Photo/The Lowell Sun & Robin Young)